Whitney P. Witt, PhD, MPH is a child health services researcher and a new faculty member at Northwestern University. This proposed NICHD KOI Mentored Research Scientist Development Award will provide the necessary support to facilitate Dr. Witt's successful transition from a junior to independent investigator in the field of child and family population health research. Her long-term goal is to develop an interdisciplinary research program dedicated to improving the health and mental health of children with chronic conditions and their families through better understanding how childhood chronic illness affects family members over time. This goal will be achieved through a 5-year program of didactic training and mentored research with two objectives: 1) to acquire new skills in behavioral biology, econometric and sociological research, and child and family demography and 2) to develop a framework of preliminary results to support an independent research proposal at the end of the award. The objectives of the award will be addressed through three specific aims corresponding to three phases of progress in Dr. Witt's career development. Aim 1 seeks to determine the relationships among child illness level, family burden, and child healthcare use and costs. Aim 2 seeks to characterize the pathways through which changes in family burden impact the health and mental health of children with chronic illness. Aim 3 seeks to determine the feasibility, performance, and comparability of biological markers of psychological stress in caregivers and caregiver-reported survey measures of stress and how such measures are related to child health outcomes. The aims of this award are designed to provide the additional experience and resources necessary to support the development of an independent R01 research proposal at the end of the award for a longitudinal study of parents and their children with chronic conditions to document the impact, both perceived and biological, of stress among caregivers, and likewise the impact of caregiver stress on the outcomes of the children they care for.